Diethanolamides



United States Patent O 3,503,891 DIETHANOLAMIDES Richard F. Schimbor, San Francisco, Calif., assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Dec. 19, 1966, Ser. No. 602,486 Int. Cl. C07c 103/00; C11d 3/32; Cm J/36 U.S. Cl. 252-152 4 Claims ABSTRACT OF THE DISCLOSURE Diethanolamides of alkanoic acids of from 12 to carbon atoms having u-alkyl branching are liquid at substantially lower temperatures than are diethanolamides of corresponding straight-chain alkanoic acids.

PRIOR ART Diethanolamide derivatives of a variety of carboxylic acids are known in the art. Due to the great difficulty in obtaining highly purified diethanolamides, the compounds are usually observed in mixtures with the isomeric aminoesters, unreacted diethanolamine, and amide-esters wherein two molecules of carboxylic acid have reacted with one molecule of d'iethanolamine. Depending in part on the method of production, the purity of a diethanolamide sample will vary considerably. Products wherein the percent purity of the diethanolamide is greater than 90% are particularly useful and are given the designation of superamides. One substantial detriment of such superamides resides in the fact that all known diethanolamides of carboxylic acids of more than about 7 or 8 carbon atoms are normally solids at or about the temperatures at which they are typically utilized, i.e., at or about room temperature. The solid character of the higher diethanolamides is responsible for difiiculties in mixing, formulating THE INVENTION It has now been found that diethanolamide derivatives of carboxylic acids in the C to C range having a-alkyl branching in an otherwise straight-chain structure are liquid at temperatures about and substantially below normal room temperature, as are superamides comprising such diethanolamides. This is in contrast to the diethanolamides of straight-chain acids of the same numbers of carbon atoms which are normally solid at such temperatures and have melting points some 6080 C. higher than the corresponding branched-chain derivatives. The present invention comtemplates diethanolamides of an u-alkyl branched carboxylic acid of a single carbon number within the C to C range, blends of diethanolamides of carboxylic acids of this class of varying carbon number, and superamide compositions comprising the diethanolamides;

THE DIETHANOLAMIDE PRECURSOR Broadly speaking, the diethanolamides of the invention comprise diethanolamides of a-alkyl branched carboxylic acids of at least one carbon number within the C to C range. To obtain the most desirable properties of the diethanolamides, e.g., biodegradability, it is preferred that the a-branched carboxylic acids are aliphatic, acyclic carboxylic acids of only atoms of carbon and hydrogen besides the oxygen atoms of the carboxyl group, that is, the acids are alkanoic acids, and are of a straight-chain structure except for the a-alkyl branch. One class of such alkanoic acids is represented by the formula wherein m is a whole number from 1 to 5 inclusive and n is a whole number from 4 to 11 inclusive selected so that the sum of m and n, i.e., the term (m-l-n), is a whole number from 9 to 12 inclusive.

The above Formula (I) provides for acids of the C to C range wherein the alpha branch is methyl, ethyl, propyl, butyl or amyl and in most instances at least a minor proportion of acid having each type of branch is employed. A substantial proportion of the acids employed as diethanolamide precursor are a-methyl alkanoic acids, typically about 50%, with lesser amounts of the other branched-chain isomers being admixed therewith.

One convenient source of the branched-chain acids is oxidation of the corresponding aldehydes and/or primary alcohols. The aldehydes and/or alcohols are advantageously obtained from straight-chaim olefins of from 11 to 14 carbon atoms by reaction with carbon monoxide and hydrogen. The reaction can be carried out to produce aldehydes in accordance with the well known Oxo process, or can be conducted as a hydroformylation reaction in which the aldehydes initially formed are simultaneously hydrogenated and converted to saturated primary alcohols of 12 to 15 carbon atoms. In these methods straight-chain aldehydes and alcohols are generally formed along with the branched-chain products. The branched-chain or the straight-chain products can be more or less completely separated, as for example by distillation, before or after conversion of the aldehydes and/or primary alcohols to the carboxylic acids.

Suitable methods of producing Oxo aldehydes which are used as starting materials for oxidation to useful mixtures of branched-chain and straight-chain carboxylic acids are described, for example, in U.S. Patents 2,564,456 and 2,587,858. As a rule it is more advantageous to use a hydroformylation method to make a mixture of straight and branched-chain alcohols which can be oxidized to the mixture of carboxylic acids suitable for conversion to the desired diethanolamides. US. Patents 2,504,682 and 2,581,988 describe processes of this type which are suitable and U.S. 2,525,354 claims a method of alcohol purification particularly advantageous with these products.

The hydroformylation is suitably carried out in the presence of a hydrogenation catalyst, advantageously using a temperature of about 200 to 400 C. under superatmospheric pressure, preferably at least 200 atmospheres with a mole ratio of olefin to carbon monoxide to hydrogen in the range from about 1:2:2 to about :20. British Patent 638,574 describes suitable methods of operation using cobalt, copper, nickel, or ruthenium and their carbonyls as cataylsts. More advantageous results as regards proportions of straight-chain and alkyl substituted alcohols can be obtained, however, by use of the complex metal carbonyltertiaryorgano catalysts containing phosphorus, arsenic, or antimony whose use in hydroformylation is described in Belgian Patent 606,408. Especially preferred are the cobalt-carbonyl trialkylphosphine where R is alkyl of 1 to 20 carbon atoms, preferably 2 to 6 carbon atoms, and a and b are integers each equal to at least 1 and whose sum is 4. Two of the Rs can be joined to provide a heterocyclic phosphine and the catalyst can be in the dimer form. These give exceptionally good results in the process of the present invention, particularly since production of the desired alkyl-substituted primary alcohols can be promoted by controlling the ratio of phosphine to cobalt in the complex carbonyl catalyst. Ratios in the range of about 2.5 to 0.5 atoms of phosphorus per atom of cobalt are useful with ratios between about 2 and about 0.8 being generally more advantageous.

The initially produced aldehyde or alcohol mixture is oxidized to the corresponding carboxylic acids of 12 to 15 carbon atoms by known methods. U.S. Patent 2,010,358, for example, describes a method of oxidizing isoaldehydes which is especially suitable for use in making the branched-chain acids. Alcohols are oxidized to aldehydes by the methods of U.S. 2,042,220 and U.S. 2,883,426 for instance, and the aldehydes are then oxidized to the branched-chain carboxylic acids. Alternatively, the branched-chain alcohols from the hydroformylation reaction are oxidized directly to the corresponding branched-chain carboxylic acids.

The required branched-chain carboxylic acids are also produced from olefins of 11 to 14 carbon atoms per molecule by carboxylation with carbon monoxide and water using, for example, nickel carbonyl and a tertiary phosphine to catalyze the reaction. A suitable method of carrying out this reaction is described in U.S. 2,658,075, for instance. By conducting the carboxylation in the presence of an alcohol, ester precursors of the desired carboxylic acids can be obtained instead of the free acids. This method of operation is advantageously carried out as described in U.S. 3,168,553, for example.

It is evident that by starting with an olefin of a single carbon number, a carboxylic acid of a single carbon number will result. However, it is also useful to employ a mixture of olefins of differing carbon numbers within the C to C range and thereby obtain a corresponding mixture of carboxylic acids of differing carbon number.

THE DIETHANOLAMIDES In terms of the preferred a-alkyl branched alkanoic acids of the above Formula I, the diethanolamides of the invention are represented by the formula wherein m and n have the previously stated significance. In one modification, the diethanolamide comprises a derivative of an alkanoic acid of a single carbon number of the C to C range, e.g., a N,N-bis(2-hydroxyethyl) dodecanoamide, although it should be appreciated that the acid moiety comprises radicals of varying structure because of the possible differing number of carbon atoms 4 in the a-alkyl branch. Thus, the diethanolamides of C acids are generically represented by the formula (III) wherein m and n have the previously stated significance and the sum of m and n is 9. Similar representative formulas illustrate the diethanolamides of the C C and C alkanoic acids.

It is, on occasion, useful to provide blends or mixtures of .diethanolamide derivatives of differing carbon number within the C to C range. Useful mixtures of diethanolamides of acids having 12, 13, 14 and/or 15 carbon atoms have from 0% to about 60%, based on total diethanolamide, of amide derivatives of acids of each carbon number. Illustrative mixtures of diethanolamides include those derived from C and C acids, from C and C acids, from C C and C acids, from C C and C15 acids and fr m C12: C13, C14 and C15 acids.

In one preferred modification of the diethanolamide mixtures, there is present at least a portion of diethanolamide of acid of even carbon number, i.e., of at least one of C and C acids, and at least a portion of diethanolamide derived from acid of an odd carbon number, i.e., at least one of C and C acids, wherein the percentage of diethanolamide of acid of even carbon number and the percentage of diethanolamide of odd carbon number is each at least of about 10% based on total diethanolamide. An additional preferred modification comprises mixtures of diethanolamides of acids of each of 12, 13, 14 and 15 carbon atoms with the percentage of diethanolamide derived from acid of each carbon number being from about 10% to about 40% based on total diethanolamide.

DIETHANOLAMIDE PRODUCTION In the production of diethanolamides broadly, numerous methods are available. In the production of the diethanolamides wherein the acid moiety incorporates an a-alkyl branch, however, best results are obtained when the diethanolamide is produced by reaction of diethanolamine with the acid chloride corresponding to the acid whose amide is desired. The acid chloride is prepared from the acids of the above Formula I by conventional methods, e.g., reaction of the acid with thionyl chloride.

To prepare the desired diethanolamide, the diethanolamine and acid chloride are contacted in a non-gaseous phase. Best results are obtained when the contacting is conducted in an inert, liquid reaction diluent such as aliphatic ketones, particularly lower alkanones such as acetone, methyl ethyl ketone or the like, and the reaction mixture is preferably anhydrous. Typical reaction temperatures are from about 25 C. to about C. and any convenient pressure is satisfactory so long as the reaction mixture is maintained in a non-gaseous state.

The method of contacting the amine and the acid chloride reactants is of importance in the production of diethanolamides of relatively high purity. It is highly desirable to conduct the contacting in such a manner that the diethanolamine reactant is always present in a molar excess. One method by which this objective is accomplished is to employ a molar ratio of diethanolamine to the acid chloride reactant of from about 2:1 to about 8:1 and adding the acid chloride to the amine in increments while employing stirring or other means of agitation to insure adequate reactant contacting and a reaction rate substantially equal to the rate of acid chloride addition.

Subsequent to reaction, the excess diethanolamine is separated and is suitably recycled and the diethanolamide product is separated and purified by conventional means such as fractional distillation and selective extraction.

DIETHANOLAMIDE COMPOSITIONS The diethanolamides of the invention are frequently employed in compositions with other materials, particularly materials which are inherently present because of the method of production and whose separation from the amide product is diflicult and/or unnecessary for efficient utilization of the diethanolamide. For example, the alkanoic acids which'are employed as amide precursors will on occasion contain a minor proportion, typically less than 5% and preferably no more than about 25%, of straight-chain alkanoic acid. In the overall process of amide production, any straight-chain acid is converted to the acid chloride and thence to the diethanolamide. In the production of the amide, a certain proportion of the acid chloride will react with a hydroxyl group of the diethanolamine to produce an ester rather than the desired amide. There also exists the possibility of reaction of two molecules of acid chloride with one molecule of diethanolamine to produce a corresponding ester-amide. In addition, amide products are, on occasion, diluted with a certain proportion of unreacted diethanolamine.

In practice, however, the presence of these impurities is not detrimental provided that the quantities thereof are not excessive. Although total purification of the diethanolamide product is accomplished only with great difficulty, conventional purification procedures result in commercially acceptable compositions of the superamide class, that is compositions wherein the percentage of diethanolamide is at least 90%.

Diethanolamides of fatty acids have established utility as components of detergents, particularly heavy-duty cleaning compositions. The amides are employed as additives to hydrocarbon oils and the like to serve as corrosion inhibitors, are applied to the surface of ponds, lakes and other standing water to retard surface evaporation, and are useful in cosmetics as emollients. It is characteristic of the diethanolamides of the invention that utilization is more facile because of the liquid character of the amides.

EXAMPLE I To a mixture of 78 g. of diethanolamine and 100 ml. of acetone in a glass reactor was slowly added a solution of 61.6 g. of tetradecanoyl chloride in 100 ml. of acetone. The acid chloride was more than 95% of the a-alkyl branched structure, of which approximately 54% had an u-methyl branch, approximately 16% had an a-ethyl branch and approximately 13% had an a-propyl branch. The resulting mixture was vigorously stirred and the rate of addition of the acid chloride solution was adjusted to maintain the reaction temperature at 45 C. At the conclusion of the addition, the stirring was continued for 1 additional hour.

The acetone diluent was removed in a rotary evaporator and the resulting oil was taken up in chloroform, extracted three times with aqueous hydrochloric acid and washed with water until the washings were neutral. The chloroform was then removed in vacuo (45 C. at 0.5 mm.) to afford 73.6 g. of a viscous, colorless liquid. This represented a yield of diethanolamide of 93.5% based on the acid chloride charged.

The infrared spectrum of the product showed a strong absorption band at 1618 cm.- which is characteristic of the amide carbonyl moiety. A shoulder at 1730 cm.- indicated the presence of an ester. The ester concentration of the product was estimated at about 4% by comparison of the relative intensities of these two bands. Chemical analysis of the product by a procedure similar to that illustrated in Toilet Goods Association, Scientific Section Proceedings, 25, 3 7 (1956), showed an amide purity of greater than 90% EXAMPLE II By a procedure substantially the same as that of Example I, diethanolamides of greater than 90% purity were produced containing greater than of alkanoic acid moieties of each of the branched chain structure of 12, 13 and 15 carbon atoms. The melting point of each was determined and is given below in Table I. It should be noted that three values are given for each amide. These represent, respectively, (1) the temperature at which initial melting was observed, (2,) the temperature at which all solid had melted, and (3) the temperature at which the melt clarified. For purposes of comparison, the data of Table I include the melting temperatures of the diethanolamides of the corresponding straight-chain acids.

A mixture of diethanolamides of a-branched alkanoic acids of C C C and C carbon numbers was prepared by blending the individual amide components. The percent purity of amide in the mixture was greater than 90% and the percentage of diethanolamide derived from straight-chain acid was less than 5%. The mixture contained 25% C diethanolamide, 25% C diethanolamide, 25% C diethanolamide and 25% C diethanolamide. The mixture is pourable at -23 C.

I claim as my invention:

1. A mixture consisting essentially of at least 10% of each of two diethanolamides wherein the mixture is of liquid state at temperatures about and substantially be low normal room temperature and wherein each diethanolamide is represented by the formula H e m)... o 0H (CHz)uH- N(CH CH0H) in which m is a whole number from 1 to 5 inclusive and n is a whole number from 4 to 11 inclusive selected so that the sum of m and n is a whole number from 9 to 12 inclusive, the mixture containing no more than 60% of any one of the diethanolamide of said formula wherein the number of carbon atoms in the acid moiety is each of 12, 13, 14 and 15.

2. The mixture of claim 1 having from about 10% to about 40% of diethanolamide of said formula wherein the number of carbon atoms in the acid moiety is each of 12, 13, 14 and 15.

3. The mixture of claim 1 wherein the nurtiber of carbon atoms in the acid moiety of at least 10% of the diethanolamide is even and the number of carbon atoms in the acid moiety of at least 10% of the diethanolamide is odd.

4. A superamide composition of liquid state at temperatures about and substantially below normal room temperature and consisting essentially of at least 90% of diethanolamide of at least one acyclic alkanoic acid of from 12 to 15 carbon atoms, where at least of said diethanolamide is diethanolamide of u-alkyl branched alkanoic acid of the formula wherein m is a whole number from 1 to 5 inclusive and n is a whole number from 4 to 11 inclusive selected so that the sum of m and n is a whole number from 9 ti) 12 inclusive.

References Cited OTHER REFERENCES Fieser and Fieser, Organic Chemistry, Third Edition, Reinhold, 1956, pp. 17 and 163.

UNITED STATES PATENTS 5 MAYER WEINBLATT, Primary Examiner Lindner 260 404,5 10 252392, 403; 260404.5, 561 

